Delete blas.Order from testing code

Delete blas.Order from testing code.

 It was decided on the gonum-dev list (https://groups.google.com/forum/#!topic/gonum-dev/hS7GCpvsRqU) to only support row major matrices in the gonum/blas implementation. This commit is the first in a series to remove row major support.

This PR removes blas.Order code from the testblas package. The other packages
will follow next.